colour

col·or

1. That aspect of the appearance of objects and light sources that may be specified as to hue, lightness (brightness), and saturation.

2. That portion of the visible (370-760 nm) electromagnetic spectrum specified as to wavelength, luminosity, and purity. Synonym(s): colour.

[L.]

colour

An aspect of visual perception, characterized by the attributes of hue, brightness and saturation, and resulting from stimulation of the retina by visible photopic light levels. Note: also spelled color.achromatic colour A visual sensation resulting from a stimulus having brightness, but devoid of hue or saturation, e.g. white, grey.colour agnosia See agnosia.colour blindnessSeecolour blindness.complementary colour One of a pair of colours which, when mixed additively, produce white or grey (that is to say an achromatic sensation). Examples: green is the complementary colour of red-purple and yellow is the complementary colour of blue. Seechromaticity diagram.confusion colour's Colours that are confused by a dichromat. The colours confused by a deuteranope, a protanope and a tritanope are not the same. For example, the deuteranope will confuse reds, greens and greys, whereas the protanope will confuse reds, oranges, blue-greens and greys. Seepseudoisochromatic plates.colour constancySeecolour constancy.colour contrastSeecolour contrast.defective colour vision Marked departure of an individual's colour vision aptitude from that of a normal observer. This is indicated by various tests, e.g. anomaloscope, pseudoisochromatic plates, Farnsworth test. The following types of defective colour vision are usually recognized: anomalous trichromatic vision or anomalous trichromatism; dichromatic vision or dichromatism; monochromatic vision or monochromatism (total colour blindness), anomaly of vision in which there is perception of luminance but not of colour. Both anomalous trichromatism and dichromatism occur in three distinct forms called respectively protanomalous vision and protanopia, deuteranomalous vision and deuteranopia, tritanomalous vision and tritanopia.The causes of defective colour vision may be an impairment of a cone pigment or a reduced number of cone cells. The majority of cases of defective colour vision are inherited and thus bilateral. Acquired defects are rare, mostly tritanopic and appear in one eye or are asymmetric, and affect males and females equally. They may be due to glaucoma, retinal or optic nerve disease, drug or chemical toxicity, diabetes, retinitis pigmentosa, etc. Hence it is essential to test colour vision under monocular conditions. The inherited type occurs as a sex-linked disorder in which the defective gene is on the X chromosome. Since men have only one X chromosome while women have two, sex-linked disorders (most being X-linked recessive) affect mainly males who inherit the genetic defect from their mother. Inherited tritanopia and tritanomaly are usually autosomal dominant. For women to show the defect, both of their X chromosomes have to carry the defective gene, a rare occurrence. Defective colour vision occurs in about 8% of the male population and 0.5% of the female population. Syn. daltonism. Seeachromatopsia; anomaloscope; deuteranomaly; deuteranopia; inheritance; ChromaGen lens; X-Chrom lens; monochromat; visual pigment; protanomaly; protanopia; Kollner's rule; colour vision test; tritanomaly; tritanopia.colour fringes Coloured edges around images formed by a lens or an optical system which is not corrected for chromatic aberration.fundamental colour'sSeeprimary colours.colour inductionSeecolour induction.colour matching Action of making a colour appear the same as a given colour.metameric colour Spectrally different radiations that produce the same colour under the same viewing conditions. Note: The corresponding property is called metamerism. Syn. metamers (CIE).colour mixture The production of a colour by mixing two or more lights of different colours (additive colour mixture) or two or more pigments (subtractive colour mixture). Seecomplementary colour; primary colours.Munsell colourSeeMunsell colour system.non-spectral colour Any colour that does not exist as a single wavelength. Example: purple, which is a mixture of blue and red radiations. Seepurple.primary colour's Any sets of three colours such as, for example, red, green and blue, which, by additive colour mixture of the stimuli in varying proportions, can produce any colour sensation. Syn. fundamental colours.spectral colour's The colours produced by the various radiations of the visible spectrum. Seelight.colour space See space, colour.colour stereoscopySeechromostereopsis.surface colour Colour perceived as belonging to a surface of an object which is not self-luminous.colour temperature The temperature of the surface of an ideal black body which emits radiations of the same chromaticity as that from the source being specified. As the temperature increases, the amount of radiations increases and the source changes colour from red through to white to blue-white. Unit: Kelvin (symbol: K).colour triangleSeechromaticity diagram.colour visionSeecolour vision.colour vision, aetiology ofSeedefective colour vision.

A good deal surprised at his manner, and at this act, which exceeded the usual familiarity of even their affectionate intercourse, the colour, of which Miss Henley had been so playfully boasting, changed once or twice with rapid transitions.

Just then the Tulip Society of Haarlem offered a prize for the discovery (we dare not say the manufacture) of a large black tulip without a spot of colour, a thing which had not yet been accomplished, and was considered impossible, as at that time there did not exist a flower of that species approaching even to a dark nut brown.

Rather was it a pearl, with the depth of iridescence of a pearl; but of a size all pearls of earth and time, welded into one, could not have totalled; and of a colour undreamed of in any pearl, or of anything else, for that matter, for it was the colour of the Red One.

Moreover, when two birds belonging to two distinct breeds are crossed, neither of which is blue or has any of the above-specified marks, the mongrel offspring are very apt suddenly to acquire these characters; for instance, I crossed some uniformly white fantails with some uniformly black barbs, and they produced mottled brown and black birds; these I again crossed together, and one grandchild of the pure white fantail and pure black barb was of as beautiful a blue colour, with the white rump, double black wing-bar, and barred and white-edged tail-feathers, as any wild rock-pigeon

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